In manufacturing tires, it is general to manufacture a green case as a base component by winding an inner liner and a body ply around a shaping drum at a shaping step and then by setting bead wires. Then, a green tire is formed by fitting a belt and a tread on the external circumference of the green case. The green tire is unloaded by a handling device from the shaping step and is transferred to a warehouse. In accordance with a production plan, the green tire is transferred to a vulcanizing step after temporal storage or is transferred from the shaping step directly to the vulcanizing step without being stored in the warehouse. At the vulcanizing step, the green tire placed at a predetermined position is grasped by a handling device of a vulcanizer and is loaded into a space which is made by opening a movable upper mold from a stationary lower mold. After the closing of the molds, a bladder is expanded by the pressure of steam or the like inside the green tire as it is stretched within the space to push the external surface thereof on the inner surface of the green tire and hence, to be closely fitted on the inner surface of the green tire, whereby the green tire is heated and pressurized from outside by the molds as well as from inside by the bladder. The vulcanization shaping is terminated upon the expiration of a predetermined time.
A problem arises in that even if shaped to be accurately uniform at the shaping step, unvulcanized green tires are liable to be deformed by experiencing various handlings such as unloading, storage, loading and placement and hence that the uniformity of the vulcanized tires are deteriorated where the vulcanization is carried out with the green tire being off-centered due to such deformation. The technology descried in FIGS. 1 and 2 of Japanese, Unexamined Published Patent Application No. 2001-096534 provides an improved method for coping with the problem. Where this method is practiced, various tools become necessary for each piece of the green tires, resulting in an increase in tire manufacturing cost.
Further, as disclosed in FIG. 1 of Japanese, Unexamined Published Patent Application No. 10-076529 as well as in FIG. 1 of Japanese, Unexamined Published Patent Application No. 10-156833, it has been a practice that at the vulcanizing step, vulcanization is carried out with the green tire put between upper and lower molds of a half cup shape. Thus, the aligning of the upper mold with the lower mold has to be made after the molds are closed, that is, after the starting of the vulcanization, and such aligning cannot be made with the upper mold remaining opened before the starting of the vulcanization.
Further, as disclosed in FIG. 2 of Japanese, Unexamined Published Patent Application No. 57-199639 as well as in FIGS. 2 and 17 of Japanese, Unexamined Published Patent Application No. 09-038977, a bladder for heating and pressurizing the green tire from inside is low in aligning accuracy because it takes a cantilever support construction that extends long from the lower side as both of an upper ring portion and a lower ring portion for the bladder are driven and supported only from the lower side, so that it has been difficult to perform the center-shaping precisely. Furthermore, the off-centering between the upper and lower ring portions becomes easier to occur with the increment in the number of time in use, which makes it unavoidable to use the off-centered bladder. Moreover, drive devices and the like are concentrated on the lower side to have many equipments on the lower side, and this makes the maintenance difficult to do.
Still furthermore, although for uniform shape and uniform thermal conveyance in expanding the bladder, various improvement have been attempted to expand the bladder uniformly at the upper and lower parts thereof, such improvements have not resulted in the expected advantages due to the use of the off-centered bladder.
In addition, as disclosed in Japanese, Unexamined Published Patent Application No. 8-39568, a loading device used in loading green tires into a vulcanizer is usually provided with tire gripping claws which are telescopically movable in the radial directions of the green tire, and operates to enter the gripping claws inside an upper bead of the green tire, then to extend the gripping claws radially outward, then to lift up the green tire with the upper bead only being grasped and finally, to transfer the green tire over a lower mold. Because the deformable green tire is lifted up to be carried at its upper half, the green tire is deformed to damage the symmetry between the upper and lower sides thereof. That is, it has been difficult to load the green tire into alignment with the center axis of the vulcanizer, whereby a problem that the vulcanized tire is low in the quality of uniformity has been unavoidable.
Accordingly, it is a primary object of the present invention to provide a vulcanizing method and vulcanizer capable of performing the vulcanization in the state that upper and lower molds, a bladder and a green tire are centered.
Another primary object of the present invention is to provide a vulcanizing method and vulcanizer capable of loading a green tire into molds without damaging the shape of the green tire.
Another object of the present invention is to provide a vulcanizing method and vulcanizer capable of operating a bladder to expand symmetrically at upper and lower portions thereof and capable of preventing the alignment of upper and lower ring portions of the bladder from getting worse with the increment in the number of time in use.
Still another object of the present invention is to provide a vulcanizer which is easy to maintain, inspect and overhaul.